<p style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; background-color: rgb(255, 255, 255);">Software quality is very important, especially for&nbsp;<a href="https://en.wikipedia.org/wiki/Commercial_software" title="Commercial software" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">commercial</a>&nbsp;and system software. If software is faulty, it can delete a person's work, crash the computer and do other unexpected things. Faults and errors are called "<a href="https://en.wikipedia.org/wiki/Software_bug" title="Software bug" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">bugs</a>" which are often discovered during alpha and beta testing.<sup class="noprint Inline-Template Template-Fact" style="line-height: 1; font-size: 11.2px; white-space: nowrap;">[<i><a href="https://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span title="This claim needs references to reliable sources. (September 2021)">citation needed</span></a></i>]</sup>&nbsp;Software is often also a victim to what is known as&nbsp;<a href="https://en.wikipedia.org/wiki/Software_aging" title="Software aging" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">software aging</a>, the progressive performance degradation resulting from a combination of unseen bugs.<sup class="noprint Inline-Template Template-Fact" style="line-height: 1; font-size: 11.2px; white-space: nowrap;">[<i><a href="https://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span title="This claim needs references to reliable sources. (September 2021)">citation needed</span></a></i>]</sup></p><p style="margin: 0.5em 0px; color: rgb(32, 33, 34); font-family: sans-serif; background-color: rgb(255, 255, 255);">Many bugs are discovered and fixed through&nbsp;<a href="https://en.wikipedia.org/wiki/Software_testing" title="Software testing" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">software testing</a>. However, software testing rarely—if ever—eliminates every bug; some programmers say that "every program has at least one more bug" (Lubarsky's Law).<sup id="cite_ref-github_15-0" class="reference" style="line-height: 1; unicode-bidi: isolate; white-space: nowrap; font-size: 11.2px;"><a href="https://en.wikipedia.org/wiki/Software#cite_note-github-15" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">[15]</a></sup>&nbsp;In the&nbsp;<a href="https://en.wikipedia.org/wiki/Waterfall_model" title="Waterfall model" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">waterfall</a>&nbsp;method of software development, separate testing teams are typically employed, but in newer approaches, collectively termed&nbsp;<a href="https://en.wikipedia.org/wiki/Agile_software_development" title="Agile software development" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">agile software development</a>, developers often do all their own testing, and demonstrate the software to users/clients regularly to obtain feedback.<sup class="noprint Inline-Template Template-Fact" style="line-height: 1; font-size: 11.2px; white-space: nowrap;">[<i><a href="https://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span title="This claim needs references to reliable sources. (September 2021)">citation needed</span></a></i>]</sup>&nbsp;Software can be tested through&nbsp;<a href="https://en.wikipedia.org/wiki/Unit_testing" title="Unit testing" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">unit testing</a>,&nbsp;<a href="https://en.wikipedia.org/wiki/Regression_testing" title="Regression testing" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">regression testing</a>&nbsp;and other methods, which are done manually, or most commonly, automatically, since the amount of code to be tested can be large.<sup class="noprint Inline-Template Template-Fact" style="line-height: 1; font-size: 11.2px; white-space: nowrap;">[<i><a href="https://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span title="This claim needs references to reliable sources. (September 2021)">citation needed</span></a></i>]</sup>&nbsp;Programs containing command software enable hardware engineering and system operations to function much easier together.<sup class="noprint Inline-Template Template-Fact" style="line-height: 1; font-size: 11.2px; white-space: nowrap;">[<i><a href="https://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" style="color: rgb(6, 69, 173); background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span title="This claim needs references to reliable sources. (September 2021)">citation needed</span></a></i>]</sup></p>